99 gmc sonoma, fuel pump wont prime?

[hoot712]

i have swapped the fp relay with the horn relay, horn works fp dont, checked the fuses all good. Jumped the fp it works, truck will run till fuel runs out, just used spare batt and isolated pump from truck. any ideas other than the ecm. also the guy that replaced the pump is not sure he has the lines right on it, any links to a pic to see the layout would help. ty

 

[epiphaknee]

So it sounds like the fuel pump works with some creative wiring. Have you checked the FP ground back near the rear bumper on the driver's side. Often times that is forgotten to be reconnected and then the FP doesn't work.

Does your fuel pressure gauge work? If not, the sending unit could be shorting out the FP too but your creative wiring made in run, so that is probably not the case.